The invention relates to improvements in torque transmitting systems in general, and more particularly to improvements in so-called hydrodynamic or hydrokinetic torque converters.
A hydrokinetic torque converter which can be modified and improved to embody the present invention is disclosed, for example, in published German patent application No. 44 20 959 A1. A torque converter of the type disclosed in this published German patent application comprises a rotary housing which can be driven by the output element of a prime mover (such as a crankshaft or a camshaft of an internal combustion engine in the power train of a motor vehicle), a pump which is mounted in and is driven by the housing, a turbine which is rotatably mounted in the housing and can transmit torque to a coaxial output element of the torque converter, an optional stator which can be installed in the housing between the pump and the turbine, and a so-called lockup or bypass clutch which can be engaged to transmit torque from the housing directly to the output element.
Torque converters of the above outlined character are frequently combined with a hydraulic or hydromechanical torque sensing or monitoring device (hereinafter called torque sensor or sensor for short) which is normally designed to establish in a hydraulic supply conduit a fluid pressure proportional to the magnitude of transmitted torque. Such sensors are normally or often employed in conjunction with hydrokinetic torque converters which are designed to transmit torque from a prime mover to a continuously variable transmission (CVT). A torque sensor which is employed in conjunction with a hydrokinetic torque converter for controlled transmission of torque to a continuously variable transmission serves to ensure that one or more force transmitting parts are automatically acted upon with a pressure which is a function of the torque to be transmitted by the transmission.
A continuously variable transmission with two adjustable sheaves or pulleys and an endless flexible torque transmitting element (such as a chain or a belt) trained over the pulleys is disclosed, for example, in published German patent application No. 42 34 294 A1. A torque sensor is associated with at least one of the adjustable pulleys in order to ensure that the arcuate portion of the endless flexible element which is trained over the at least one pulley is clamped with a force which is proportional to the magnitude of the torque to be transmitted by the respective pulley. For example, the torque sensor can comprise preferably spherical rolling elements cooperating with surfaces arranged to transmit clamping and/or other forces related to the ratio of and to the torque to be transmitted by the torque converter.
As a rule, a torque sensor is installed next to the housing of a hydrokinetic torque converter, for example, between the torque converter and a continuously variable transmission. Reference may be had, for example, to pages 181-196 of the 1990 edition of German "VDI-Berichte" (meaning: Reports by the Association of German Engineers). A drawback of such mounting of a torque sensor is that, though it is or can be made readily accessible, it contributes significantly to the bulk of the power train, especially as considered in the axial direction of the torque converter.
Reference may also be had to commonly owned U.S. Pat. No. 5,667,448 granted Sep. 16, 1997 to Oswald Friedmann for "POWER TRAIN". The patented power train employs a torque sensor which is installed between two torque transmitting systems in the form of clutches and an adjustable pulley of a continuously variable transmission. That clutch which is at least partially engaged receives torque from the output shaft of a prime mover, e.g., an internal combustion engine in the power train of a motor vehicle. In a motor vehicle wherein the space under the hood is at a premium, the placing of a torque sensor as a discrete part between neighboring constituents of the power train is likely to increase the overall axial length of the power train to an extent which renders the power train unsuitable for use in certain types of motor vehicles.
U.S. Pat. No. 4,577,737 (granted Mar. 25, 1986 to Niikura et al. for LOCK-UP TORQUE CONVERTER AND METHOD FOR CONTROLLING CLUTCH SLIP IN LOCK-UP TORQUE CONVERTER) discloses a hydrokinetic torque converter with a lockup clutch and an electromagnetic torque sensor which is surrounded by the pump as well as by the turbine of the torque converter and is installed radially outwardly of the radially inner portion of the piston of the lockup clutch. Such distribution of the pump, turbine, lockup clutch and torque sensor in the housing of the torque converter contributes significantly to the space requirements of the torque converter, particularly in the radial direction of the housing.